\documentclass[12pt]{article}
\usepackage {verbatim}
\begin{document}
\title{ Simple \LaTeX Document}
\date{}
\author {Tesfaye}
\maketitle
\center {This is text centred}
\section {Title}
\subsection{Introduction}
In this paper 
we will produce some simple 
mamthematical formulas.
\begin {equation} 
\label{eqn:i}
\sum_{i=1}^n i 
\end {equation}
 
\begin {enumerate}
\item This is item 1
\item This is item 2
\item This is item 3
\end {enumerate}

\center {This is the code I used to demonstrate the functions}
\begin {verbatim}

 #include <stdio.h> 

const int n=1000;
void populateData (int* dataarray, int sz);

int main (int argc, char** argv){

int intarray[n];
populateData(intarray, n);

return 0;
}
void populateData (int* dataarray, int sz){
for(int i=0; i<sz; i++){
  dataarray[i]=i;
}

}
\end {verbatim}
\end {document}
